Changes in the heritable attributes of populations of organisms over time. Major mechanisms include drift, natural selection, mutation, and gene flow (migration).

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How can the number of chromosome change during evolution

I found an explanation here, which is basically saying that sometimes the centromeres are duplicated, breaking a chromosome into two halves. But how could this propagate? I don't think inbreeding is ...
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1answer
401 views

Did spiders respond to light for building webs before artificial light was invented?

I have noticed that during summer, beautiful spider colonies grow wherever a strong light is: I'm wonder whether spiders evolved to seek naturally lighted areas where they build nests (before ...
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31 views

Are there any biological obstacles prohibiting lighter-than-air organisms? [duplicate]

Why there are no organisms that use cavities filled with lighter-than air substances (e.g. hydrogen) to fly and remain in air? Given that there are a lot of fish and algae that use similar cavities ...
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Why do some animals have 8 Limbs (e.g. Spiders, Octopuses)?

Octopuses have 8 tentacles, spiders have 8 legs. Is there something special about 8? It seems like an animal that needs 360° mobility has 8 legs.
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428 views

Why are lions the only social cats?

We know that almost all cats are solitary. How did the Lions (Panthera leo) end up social animals? Do we have an explanatory evolutionary path describing how the Lions became social while the rest of ...
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1answer
236 views

Are there examples of now-living species where one is descended from the other?

I'm not a biology person so please forgive me if this question is formulated badly :) I'm curious. Are there any species that has an ancestor species that is still alive today?
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60 views

Have there been any macro-evolution experiements?

I'd like to start first by saying that I don't believe in creationism at all, nor any non-Darwinian-evolution explanation of the diversity of life on Earth. The theory, the fossil record, and the ...
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1answer
365 views

Why are many fruits sour?

Many fruits (like apples, berries, citrus fruits etc.) contain high levels of organic acids, especially malic acid and citric acid. Are there any evolutionary functions of those acids in ripe fruits? ...
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2answers
89 views

Why we have to damage our muscles to build them?

I know that new muscle cells are made when actin fibers are disrupted. My hypothesis is that muscle mass is limited, from birth, and that nutrients (protein) are only directed to grow muscle when ...
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1answer
35 views

Genome Sequencing [closed]

Is Genome sequencing used to determine the relationship between two species that are believed to have a common line of descent? How accurate is this method if so? Are there more accurate methods ...
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1answer
79 views

Bootstrap question

I have a question about bootstrapping: The way that I understand it is that each number represents how well a given node is supported. So in the diagram presented, we can see that the ...
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0answers
20 views

Relationship between selection coefficient and frequency of elimination

I'm asking this question because I would like to model the influence of changes that take place during tumour evolution to estimate what changes are selected against. I am in effect looking at ...
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1answer
77 views

Why isn't the biological niche occupied by whales instead occupied by fishes?

As by the title. Why aren't there many more, and larger, whale shark like creatures instead of the great mammalian swimmers? I'd assume fish have a benefit in doing the whole "being under water" thing ...
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105 views

Why don't we have two hearts? [duplicate]

The human body is amazing. But there seems to be some evolutionary changes that appear to not make sense regarding redundancy. While not necessarily the primary reason for their existence, the human ...
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1answer
211 views

“selective pressure” or “selection pressure”?

Editing a manuscript of mine, a co-author changes "selection pressure" to "selective pressure". Are those two terms interchangeable? Or are there subtle differences that I'm not aware of? The ...
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0answers
11 views

What explains the different nutrients of seeds?

I was eating a orange while at work and thought to myself, "Why are oranges sugary, and avocados fatty?" They functionally both do the same thing, right? So my thoughts are simply that this is ...
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1answer
380 views

Is sexual selection evolutionarily advantageous?

Our biology teacher says that peacocks will soon become extinct because of bigger and bigger (and heavier and heavier) tails. Why natural selection did not eliminate sexual selection?
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15 views

Rates of evolution of mitochondrial genes

I am interested in knowing the rates of evolution of different mitochondrial genes (in base pairs per million years) across different taxa. Has there been any publications along these lines ?
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1answer
525 views

Why have whales and dolphins not evolved to have gills?

It seems at first glance that it would be an evolutionary disadvantage for a sea creature to have to come up to the surface on a regular basis in order to breathe, so why are there animals (e.g. ...
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1answer
119 views

Why do we breath oxygen? [closed]

I like this contradiction. But seems like my Biology teacher doesn't. If oxygen oxidates us, why do we breath it? Why can't we evolve into a new kind of human being that breaths other component of ...
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1answer
5k views

Why do we grow so much hair on our heads compared to our bodies?

I've been wondering about head hair, facial hair in particular. Human males can grow very extensive beards should they choose to not shave - however you do not really see this in our chimpanzee ...
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2answers
212 views

Why do squirrels have twitchy bushy tails?

Whenever I see a squirrel in the woods, it is always the big bushy tail flipping around that gets my attention first. A pray animal with a big bushy flag calling attention to it's self seems to be ...
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1answer
109 views

Are there examples of animals that adapt to their environment very quickly? The phenomenon is called Phenoptic Plasticity [closed]

Evolution and speciation may take millions of years. This made me wonder if there is an animal that adapts itself relatively rapidly to its environment? I don't mean a simple adaptation like a change ...
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2answers
235 views

Why are there so many different humans yet chimpanzees are just chimpanzees?

There are two species belonging to the Pan genus (Pan troglodytes and Pan paniscus). That's just two. I mean, humans have changed radically since we split from chimpanzees, we have Australopithecus ...
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1answer
85 views

Question on Evolution [closed]

Scientists say there are 15 million insect species, 2 million marine species, more millions of bird and animal species. Yet, only one- humans - developed language. If evolution is true - that species ...
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2answers
625 views

Why does sexual selection evolve beautiful features?

I have a very raw understanding of sexual selection: Say a group of females of a certain species "likes" some feature of a certain groups of males; by "like" I mean some behaviour that makes this ...
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3answers
172 views

Did we evolve from monkeys?

Since I was young, I always understood that evolution taught that we descended from monkeys (or apes, not too sure a distinction was ever made). However, someone recently told me that this isn't ...
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3answers
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Chromosome 2 fusion?

I read this article by Jeffrey Tomkins and Jerry Bergman claiming to debunk chromosome 2 fusion. Is there anything wrong with these conclusions? " 1.The reputed fusion site is located in a ...
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0answers
70 views

Why did life on Earth develop with two sexes? [duplicate]

If evolution gives us the best adapted organisms for survival of the fittest, why does so many of Earth's organisms require two sexes for reproduction? Shouldn't this have been bred out of our ...
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2answers
200 views

DNA adaptation in human life

Does our DNA adapt by human lifetime? Or do we have the same genetic information from birth to death? I mean: What is usually called "evolution" means "natural selection" like this: ...
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1answer
208 views

Sequence evolution simulation tool

I'm looking for a tool to simulate sequence evolution given a specific mutation model and birth-death model. I'm aware of tools and packages like INDELible, Seq-Gen and PhyloSim, but they simulate ...
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1answer
617 views

Evolution home experiment?

If I were to take bakers yeast and put it in medium of minimal sugar(whatever quantity that would be) and rice(for a source of starch), could the yeast have a "evolutionary leap" and adapt to use the ...
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140 views

How did the first life form on Earth reproduce without DNA?

So, the best explanation I can think of for the first life form, life happening from nothing (wow), is that over billions of years, with trillions of water molecules and dust particles and chemicals ...
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6answers
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Why do plants have green leaves and not red?

I know plants are green due to chlorophyll. Surely it would be more beneficial for plants to be red than green as by being green they reflect green light and do not absorb it even though green light ...
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1answer
43 views

Biological Evolution outside of Earth [closed]

What drives evolution forward? I heard that climate change drives species to evolve and adapt. Is there any other mechanism that is encoded in our DNA by which species can over abrupt changes, evolve ...
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1answer
44 views

Who was the first to coin the terms of soft and hard selection?

Soft and hard selection are sometimes used with different definitions. I have been told that at first place hard and soft selection has been defined in the following way: soft selection: Each deme ...
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1answer
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Is the fixation rate always equal to the mutation rate for neutral alleles?

Background A classical result of population genetic is that the rate of fixation of netreual alleles is the mutation rate $\mu$. The reason is that each generation $PN_e\mu$ mutations enter the ...
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2answers
948 views

Why can't we call dog breeds different species?

I understand this question might fall into opinion based, but I'm trying to write it so that it meets the "Many good questions generate some degree of opinion based on expert experience" part and not ...
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2answers
289 views

Why don't we keep evolving until we are super-human? [duplicate]

Humans (homo sapiens) have been on the earth for thousands of generations, and we have kept evolving throughout that time. Why don't we just keep evolving so that, let's say, we live for an average of ...
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2answers
2k views

Why did humans lose their fur?

The little amount of body hair humans have don't seem to be of much use for keeping warm. Our Simian cousins on the other hand sport thick furs. At which point during the species evolution and why ...
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1answer
24 views

Endothermy in different species

Birds and mammals are both endothermic, meaning they metabolically generate the heat they need to keep their body within a certain temperature ranger. But birds are closer relatives to reptiles than ...
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42 views

What are constrained genetic elements?

I am somewhat of a newbie in evolutionary biology currently taking my first steps in bioinformatics. I was reading a paper when I came across the term "constrained genetic elements", referring to ...
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1answer
176 views

What is a selective constraint?

I encountered the term selective constraint in Huber et al. 2015, page 4 (last paragraph) in: If invariable sites are included in the analysis, then both the methods of Kim and Stephan ...
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1answer
80 views

What factors cause males to be more common than females in humans, from an evolutionary perspective? [duplicate]

Fisher's principle states that there should be a 1:1 ratio between males and females born on average for a population. However, if you look at birth statistics your find that boys are slightly more ...
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40 views

Evolution of blood types [duplicate]

What are the popular theories regarding how our blood divided into 4 groups. Particularly I'm interested in whether this was originally linked to disease. Thanks for your answers, useful articles and ...
2
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1answer
74 views

Do all mammals have a Ventricular system?

I am familiar with the human Ventricular system that circulates Cerebrospinal fluid. This is needed among other reasons, to suspend the heavy human brain, and for injury protection. Do all mammals ...
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44 views

Variance in reproductive success and effective population size

Background The effective population size $Ne$ is the size of the Wright-Fisher population that experience the same amount of drift than the population under consideration. The higher the variance in ...
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1answer
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Why does a coconut have exactly three holes

A theory says: As coconut is a sibling of palm, somehow long time ago, three palms were in a same husk. Based on evolution theory, it's how the coconut was born in the world with three holes. ...
6
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1answer
160 views

Effects of selection on effective population size

Background The effective population size ($N_e$) is a central concept of evolutionary biology and is influenced by several parameters. For example: sex ratio bias affects $N_e$ $\left(N_e = ...
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3answers
202 views

Why does all life use the same macromolecules in their genetic code?

There is no biochemical constraint of any sort, so why doesn't some other code work? Why is it specifically RNA/DNA?